Electrode catheters have been in common use in medical practice for many years. They have been used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity. More recently, therapeutic and diagnostic agents have been delivered into the heart, including the heart wall, through a percutaneous transluminal approach with the use of catheters. In particular, catheters with a needle have been used for injection directly into the myocardium for a variety of treatments, including myocardial revascularization. For example, U.S. Pat. No. 6,309,370 entitled Intracardiac Drug Delivery, the entire disclosure of which is hereby incorporated by reference, is directed methods and apparatuses to provide accurate minimally-invasive methods and apparatus for intracardiac administration of drugs to the myocardium.
In use, the electrode catheter is inserted into a major vein or artery, e.g., femoral artery, and then guided into the chamber of the heart of concern. Navigation of the catheter has been accomplished largely with the use of fluoroscopy which poses radiation concerns for both the patient and the treating physician. Moreover, within the heart, the ability to control the exact position and orientation of the catheter tip is critical and largely determines how useful the catheter is. Electromagnetic position sensors have been in use in catheter tips for many years. While these sensors provide useful data to determine location and position of the catheter, they can be relatively large and consequently tend to occupy a significant amount of space in the catheter tip.
In recent years, magnetically navigable and controllable catheters have been used. These catheters have allowed more aspects of ablation and mapping procedures to be automated for improved accuracy and efficiency. They also provide the benefit of lowering radiation exposure at least for the treating physicians by enabling catheter control from a remote location away from the patient. However, because space in the catheter tip is at a premium, the integration of ablation, mapping and injection capabilities with magnetic navigation in a catheter tip has been challenging. While such catheters exist, the catheter tips tend to lack sufficient volume of magnetic material for adequate magnetic navigation and control and their needle ports have been generally eccentric or off-axis. Moreover, the injection needle is generally made of a relatively stiff material that allows the translation of force to enable the extension. However, added stiffness tends to make it more difficult to adequately deflect the catheter without increasing magnetic volume. The action of injection requires the tip of the catheter to remain in contact with tissue surface. Insufficient magnetic “adhesion” force would limit the ability of the needle to penetrate tissue.
Accordingly, it is desirable to provide a magnetically navigable and controllable catheter whose tip section carries adequate elements for ablation, mapping and injection. Particularly desirable is a catheter having a tip section with an omnidirectional tip electrode and a concentric needle port for greater tip angulation while housing a position sensor and a sufficient volume of magnetic or magnetizable material to enable suitable magnetic response to an external magnetic surgery system.